Why Are Opossums Living So Long?

Professor Steven Austad is a distinguished researcher in geroscience and the Protective Life Endowed Chair in Healthy Aging at the University of Alabama at Birmingham. He's also the Director of the Nathan Shock Center at UAB and the Senior Scientific Director of the American Federation for Aging Research.

Today, Professor Austad joins Bob Hughes to discuss the biology of aging. He begins by narrating the discovery that sparked his interest in aging and his transition from animal behavior to the biology of aging. He discusses how these discoveries led him to the rate of living theory—the idea that the rate of aging is determined by your metabolic rate—and explains a somewhat paradoxical aspect to this theory: the hummingbird, which has a high metabolic rate, is  relatively long-lived. He goes on to review evolutionary ideas to understand the rate of living theory, shares his striking discovery about how possums age more slowly in the absence of predation, and describes both why birds of flight live longer than terrestrial birds and the unusually long lifespan of bats.

Professor Austad talks of how natural history observations can accelerate more molecular and pharmacologic insights into human health, explaining, “Evolution is smarter than you.” He shares his perspective of the research enterprise: what we do well, what we don't do well, and how we can be better. He also details where he stands on aging in the private sector and for-profit aging companies, the mechanisms of age-related decline, and gives details about his bet with Jay Olshansky about a 150-year-old person being alive by 2150. Finally, Professor Austad reveals his expectations on whether more people will live to be more than 120 or 150 in the second half of the century due to interventions, and shares what he would focus on if he was given $1 billion.

In this episode, you'll learn about aging in animals and humans and the factors that determine their longevity. You also hear about aging in the private sector as well as  comparing today's interventions to aging with evolutionary stimulus.

Episode Highlights:

• Professor Austad's transition from animal behavior to aging
• The striking differences  in aging between a South American species of opossums and mice
• The rate of living theory
• The constant heartbeat theory—understanding the impact of heartbeat rate and longevity
• An alternative to the rate of living theory—the evolutionary approach
• Professor Austad's study and discovery on the aging of possums without predator interference
• Why birds of flight live longer than terrestrial birds
• Current estimates on bat longevity and why bats have a long lifespan
• How natural history observations can accelerate more molecular or pharmacologic insights into human health
• How evolution is smarter than humans
• Professor Austad's view of the research enterprise
• Aging in the private sector and for-profit aging companies
• Mechanisms in age-related decline
• Professor Austad's bet with Jay Olshansky about a living 150-year-old person by 2150.
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Quotes:

"The interesting thing is that project was about the sex ratio of the pups and was eventually published in Nature. And by the time it came out, I totally lost interest in that project, and I was off studying aging."

"Evolution has this wonderful capacity to take a single-cell fertilized egg and have it develop into a healthy adult in some kind of species. It would seem to be just much easier to simply maintain that healthy adult once you have it, but yet it's almost ubiquitous that when aging occurs, that healthy adult gradually loses its health."

"One of the evolutionary ideas to understand that was that evolution is all about reproduction, and what evolution will favor is whatever physiology maximizes reproductive rate."

"One of the things about possums that's important to note is that about 80% of them are ultimately killed by predators."

"So it's clear that the lack of predators had really had an impact on those opossums because they were just like the animals of the Galapagos, completely unafraid of humans."

"The longest-lived wild bat is reported to be 41 years. And that's an animal that's about a fifth the size of a mouse."

"High-frequency hearing is one of the first things we lose, but bats have to maintain that year after year after year because getting their food depends on it. They find their animals in the dark by screaming and listening for the echoes. So the fact that a bat can live over 40 years in the wild strikes me as much more impressive than if it lived 60 years in a cave somewhere."

"One of my favorite quotes is that evolution is smarter than you are. I think that's true because it's just so long to experiment. And so I think evolution will have come up with solutions to, let's say, how to maintain muscles better, maintain vision longer, or maintain nerves better in some species than we currently already do in humans."

"I think scientists are increasingly conservative because they want to be able to do something that they know works. And most people I know have at least half of their next grant proposal already done, half the research done before submitting the proposal. And that, to me, is a good recipe for incremental advances, but not a recipe for major breakthroughs."

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